A. Field of the Invention
The field of the present invention relates generally to conveying systems wherein the conveyor is actively operative to off-load products from the conveying surface. More particularly, the present invention relates to such conveying systems that utilize pneumatic diverters to selectively off-load products from the conveying surface. Even more particularly, the present invention relates to such conveying systems and diverters that are specially configured for use with small and easily damaged products, such as small spherical and ovular shaped fruit and the like.
B. Background
As is generally known, many products are available in different sizes, shapes and levels of quality. This is particularly true with regard to food products, including fresh, dried or processed fruit and vegetables, which must be sorted into different classifications with regard to various specific characteristics for the different types of food products. In general, product handling and sorting activities for the discrimination of individual product units have been in use for some time, particularly in the food product industry. Discrimination of product units in the food industry is generally based on certain selected product qualitites, including such qualities as the size, ripeness and color of the product and/or the amount and type of blemishes and the like on the product. Until somewhat recently, the handling and sorting of products, particularly food products, was primarily accomplished through the use of manual labor by having products conveyed past workers at individual work stations so the workers could review and separate products based on the selected criteria for that product. A principal benefit of manual labor is the versatility of the worker in being able to handle and make selections for different types of products. As is well known in the food industry, however, such labor has become generally more expensive and, due to its seasonal nature, it can be somewhat unreliable with regard to consistency. Due to the difficulties in finding experienced seasonal workers and the normal administrative problems associated with a fluctuating work force, there has been a need for less labor intensive systems.
With regard to automated product handling systems for the food industry, the nature, volume, relative unit cost and variety of different types of food products severely inhibit the ability to design product handling equipment that is uniformly applicable to different foods. Naturally, due to the nature of food products, particularly most fresh fruit and vegetables, the products must be handled with great care to avoid damage to the product that would reduce its market value or, in some cases, its ability to be sold. In addition, the perishable nature and large quantities of products that need to be processed in a short period of time after harvesting makes rapid processing of the food products an economic necessity. However, due to the varied nature of food products, it is difficult for the average food processor to economically justify food processing equipment that is suitable for processing only a very limited type of food product (i.e., one type of fruit or vegetable). As a result, it is generally preferred that any automated food handling equipment which is intended to replace the versatility of the human worker must be configured for use with a number different types of food products. Unfortunately, due to the varied characteristics of food products, this places great demand for versatility on the equipment.
The availability of relatively inexpensive yet high powered computers and computer related and controlled equipment and the ability to use such equipment with ever improving optical sensing equipment has benefitted numerous product handling industries, including the food industry. The use of these computers and optical sensors, and the relatively sophisticated software available for such computers and sensors, has vastly improved the capability for detecting the size and condition of individual product units and distinguishing between the units based on the desired selection criteria. This equipment is used with conveyor lines that move the product into position for scanning and then move the product to a storage or shipping container that is appropriate for the category of product (i.e., based on the selection criteria). In conjunction with the equipment to optically scan and characterize products, the handling equipment requires the use of responsive mechanisms that rapidly respond to commands from the computerized equipment so as to off-load products from the conveyor system into the appropriate container. If the product fails to meet the minimum allowable criteria, it is generally conveyed to a separate container or location for discarding.
Automated responsive mechanisms suitable for off-loading products in response to commands from the computer and optical scanning equipment require a somewhat exacting placement of individual product units relative to the responsive mechanism, sufficient separation of product units from each other, proper orientation, and if necessary reorientation, of the product unit relative to the responsive mechanism and an ability to quickly separate the product unit from the conveying line. In separating the product from the conveying line, it is generally necessary that this be done with some care relative to the product so as not to damage the product. This is particularly a concern in the food industry and, even more particularly, with certain types of foods. In general, responsive mechanisms for larger fruit and vegetables, such as citrus, apples and tomatoes, have been in use for some time. The ability to properly handle certain types of food products, such as cherries and the like, in an automated handling system has been very limited due to their small size, relative fragility and characteristics of the product (i.e., long stems).
With regard to the typical food product handling system for fresh fruit, the products are loaded into multiple single file lanes, each consisting of linear pockets that are typically mounted on a roller chain or cables. Being generally spherical in shape, each individual fruit product will generally find a pocket for itself. This process is generally referred to as “singulation.” Typically, the lanes are separated from each other by a gap so that any excess fruit will fall onto a return belt. The fruit lanes proceed through an inspection box, where the fruit is illuminated by radiation, typically by fluorescent lamps, and inspected by sensors, which are typically black and white or color area array video cameras of medium resolution. If the pockets comprise rotatable rollers, the fruit may be rotate during the inspection process to allow different sides of the fruit to be analyzed. The camera video signal is digitized and analyzed by a computer. The fruit pockets are tracked by the computer using a shaft encoder monitoring the progress of the pocket lanes. The images are analyzed to obtain the diameter/size, average color (i.e., green, yellow, orange), surface defects and/or other information pertinent to the particular fruit. The operator of the system has a console where he or she selects which combinations of size/color/defect grade are to go to each output belt on the grader. These output belts generally pass perpendicularly under the lanes such that when the fruit/pocket reaches the proper output belt, a computer controlled electrical device is activated to trigger the responsive mechanism so that it lifts, pushes or drops the fruit out of the pocket where it falls onto the moving output belt.
Referring to the related patents discussed below, various responsive mechanisms evolved to remove the fruit from the lane. For larger fruit, the generally preferred system has flippers and a connected lever arm that is mounted between each roller at the bottom of the pocket. When the fruit is at the ejection point, a solenoid actuator trips the lever arm into a different channel such that the chain motion causes the flipper to rotate up from one side, thereby pushing the fruit off the other side of the pocket and onto the belt.
An early automatic sorting system for handling of products is disclosed in U.S. Pat. No. 4,106,628 to Warkentin et al., which describes a plurality of cups arranged on a chain conveyor for holding individual product units. Solenoids act to dump selected cups for product separation responsive to discriminating sensing and electronic commands. U.S. Pat. No. 4,961,489, also to Warkentin, discloses a product handling system having a conveyor that includes elements capable of tipping to off-load individual units of a product being processed. The nature of the conveyor permits some variety in shapes and sizes, including elongated products. However, a range of round or oval products in smaller sizes is not as easily accommodated by this system. U.S. Pat. No. 5,474,167, also to Warkentin, discloses an off-loading conveying system having off-loading elements mounted to endless roller chains. The off-loading elements include levers to pivot paddles extending between bow tie rollers so as to remove the product at the appropriate stations. The system is particularly configured to handle small, easily damaged spherical and ovular shaped product units in a high-speed, electronically controlled processing stream of product units. U.S. Pat. No. 4,595,091 to Scopatz et al., describes an article diverter having an ejector lever member for rapidly and gently diverting articles such as fruit from a moving conveyor.
Other product handling systems include devices for batting, tipping, pushing, dropping, blowing or otherwise depositing selected product units from the lane conveyors to the output belts or containers. The use of a pneumatic air system to blow large fruit of the side of cables with a single port nozzle has been tried. However, this system is believed to have failed because the air damaged the larger fruit and the amount of air needed to operate the system required unfeasibly large compressors. Others, such as Key Technology and SRC Vision have used a horizontally space air nozzle array to divert small items falling off the end of the conveyor. Blueberry Equipment Incorporated has an electronic sorter that ejects defective units, such as blueberries and cranberries, by blowing them straight up as they pass by between two cables. A single port nozzle is used between each cable. Because this could harm some fruit, they are generally only used for good versus bad separation.
With regard to certain types of products, however, the mechanical devices typically utilized have certain problems. For instance, cherries typically have one to two inch long stems that can become caught in mechanical diverters, such as the chain mounted removal mechanisms. Consumer market cherries are generally sized into four different sizes. Because of the long stems, a special sizing system for cherries has been developed and is now used universally. This sizer organizes the incoming cherries in rows and each row enters the valley formed by two long tubes about six to eight ft long. The axis of each tube is about 45 degrees downward, so the cherries then tumble down. The spacing between the tubes widens as they tumble down, with the smaller ones (smallest size) passing through first, onto a belt, and so on. The rolls are also counter rotating to keep cherries from jamming. There are several variations of this basic two tube system designed to improve the sizing accuracy, which is particularly difficult, as the diameter of each packed size are quite close to each other. For instance, the smallest size for Bing type cherries is 12 Row, with a minimum diameter of 54/64 inch, the minimum for a 11½ Row is 57/64 inch and the 11 Row is 61/64 inch. The other complicating thing is that the cherry diameter is the maximum diameter as viewed by looking straight down from the stem end. In most cases, this diameter is the largest width on the cherry, as they are three dimensional fruit. In general this diameter is not what is actually measured by the mechanical cherry system used as described above. Electronic sizing systems using video cameras could find the correct diameter more reliably.
Although the prior art discloses product handling systems for handling and sorting small, somewhat delicate fruit such as cherries and the like, none of the presently known product handling systems provides a responsive mechanism or diverter particularly suitable for sorting small, relatively delicate products, such as cherries and the like, into closely separated categories according to selected characteristics of the products (i.e., size, color, quality and etc.). The known mechanical devices and pneumatic devices do not function as desired. What is needed, therefore, is a small item diverter mechanism suitable for rapidly responding to electronic commands to cause products to be sorted according to selected criteria.